SBC DSL Modem is not functioning... DSL light is flashing red?

Hello,

I have a very ancient (5 year old) Speedstream 5100 SBC DSL modem connected to my computer. The main cable is connected to the wall. Just yesterday I came home from school and noticed the DSL light was flashing red. This means to me that I wont be able to get on the internet. I checked all the wires and they were in place, I even unplugged the modem's power and waited a good 3 minutes before plugging everything back in. Nothing worked. I called my internet service provider, ATT, and spoke to someone for like, 2 hours. They ran 5 or 6 tests to see if anything was wrong where I was, like if the lines were functioning. They made me reset the modem, try to activate it again, take the modem to another room with a phone jack and plug it in there, and that test failed too. The DSL light was still flashing red. The power light is green, ethernet light is green, DSL light blinking red, internet light off, and activity light blinking green. What could be the problem with my modem? Do I need to buy a new one?

please help! I'm a college student and need the internet! I'm actually at my institution working on their computers. (R.N. Registered Nursing Major).

thanks a bunch,

haphazard_artist